1. Field of the Invention
This invention relates to the preparation of 1,2-cycloalkanediones and is more particularly concerned with the preparation of 1,2-cycloalkanediones by autoxidation of the corresponding cycloalkanones.
2. Description of the Prior Art
A number of methods for the preparation of 1,2-cycloalkanediones are known. Illustratively, 1,2-cyclohexanedione has been obtained by brominating cyclohexanone and hydrolyzing the 2,6-dibromocyclohexanone to the corresponding dihydroxycyclohexanone which then loses water to yield the dione; see Wallach et al., Annalen 437, 172, 1924. 1,2-cyclohexanedione has also been obtained by heating divinyl glycol with copper (Urion, Comptes rendus 192, 1662, 1931) and by oxidizing cyclohexanone with selenium dioxide in ethanolic solution (Riley et al., J. Chem. Soc. 1932, 1875). A procedure involving the oxidation of cyclohexanone with selenious acid or selenium dioxide in aqueous dioxan is described in Organic Synthesis, Collective Volume IV, 1963, 229, John Wiley and Sons Inc., New York.
We have now found that 1,2-cyclohexanedione and like 1,2-cycloaliphatic diketones can be prepared readily and in good yield by autoxidation of the corresponding cycloalkanones using readily available and inexpensive reagents.